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age drop is also not determined depending on the rated current The flush-mounted enclosure should be installed at the cable
of the overcurrent protective device, but on the operating cur- tray if the light strips described above are mounted next to a
rent of the luminaires. ceiling (Figure 9.25.3).

In practice, type 3 surge arresters are used to protect small-sized If powerful light strips are supplied with three-phase current
light strips operated with alternating current with backup fuses (nominal current > 25 A) via long cable distances, larger cross-
up to 16 A (Figure 9.25.1). Thanks to their compact design, sections must frequently be installed due to the voltage drop
these surge arresters can be installed in the luminaire housing. and the loop impedance. In such cases, the cable cross-section
close to the connection point of the light strip is reduced to the
For light strips operated with three-phase current with backup cross-section to be connected to the terminal (in the majority of
2
fuses up to 25 A, it is advisable to use DIN rail mounted type 3 cases 2.5 mm ) via a junction box. To this end, it is advisable to
surge arresters in a flush-mounted enclosure with an adequate install type 2 surge arresters which are available for TN-S and
degree of protection which can be directly installed on the DIN TT systems. These surge arresters may only be used for backup
rail (Figure 9.25.2). This type of installation is recommended for fuses up to max. 125 A which is out of the question due to the
the supply lines of pendent luminaires (length of several metres). short-circuit load on the light strip wiring.

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